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By B. O. Pickard

WITH more than a score of shafts and numerous stope openings to the surface, all inter-connected underground; with underground temperatures high, often exceeding 100° wet bulb; with an ore presenting a dust health-hazard; with certain rocks giving off inert gases; with an altitude of 6000 ft. above the sea level and a dry desert climate, the Tonopah mines offered an interesting, problem to the student of metal-mine ventilation. Tonopah is not an old mining district relatively speaking. It was discovered in 1900 and Tonopah soon was a boom camp. By 1910 the mines of this district had paid many millions of dollars in dividends. At the time of the 1921 ventilation study, mining had passed its peak of production and the operators were striving to reduce costs, to discover new ore bodies, and to attract desirable workmen. In 1925, the camp was operating on a still less prosperous basis, but the several managements had not relaxed in their efforts to keep the mines on a paying basis, neither had they lost their faith in the ability of the mines and the price of the silver to "come back." Early in the fall of 1921 the Bureau of Mines was invited by the mine operators at Tonopah, Nevada, to make a detailed study of the under-ground air conditions in the Tonopah silver district. D. Harrington,? who was then directly supervising the ventilation studies of the bureau, detailed district engineer B. 0. Pickard, mining engineer E. D. Gardner, surgeon C. E. Kindall, and petrographer H. Insley to carry on the study. G. S. Rice, as chief mining engineer of the Bureau of Mines, was in general charge of the work. Upon the completion of the study each operator was furnished a report on conditions in his mine.

Jan 2, 1927

By Frederick Laist

THE past year has witnessed no radical changes in methods for the reduction and refining of copper. The Carson litigation was finally brought to a close ant1 the copper smelter is again free to introduce charge into his reverberatory furnaces in whatever manner suits him best. This litigation naturally led to much experimentation with various methods of charging and with various types of bath. In some cases the charge was introduced more or less centrally on a relatively dry hearth and in other cases into a bath of greater or less depth. The results of these furnaces were meticulously compared with the results obtained in side-charger furnaces, and it was apparent that it made little, if any difference how a given furnace \\.as charged so long as care was taken that there was always something in the furnace for the flames to work on. So long as this requirement was complied with, consumption of fuel per ton of charge smelted and tonnage smelted per furnace day remained substantially the same regardless of the method of charging or the depth of bath employed. In some instances the center-charged deep-bath furnaces gave slightly better results than the side-charged particularly with respect to copper losses. The slags of the deep-bath furnaces are generally a little cleaner

Jan 1, 1930

By C. Y. Clayton

In connection with certain cooperative work carried on between the Ordnance Department of the U. S. Army, the U. S. Bureau of Mines, and the U. S. Geological Survey during the year 1918, it was the writers' privilege to make metallographic examinations of a great many test bars and other pieces of nickel-steel gun forgings. The material studied came from many different steel plants throughout the country and consisted both of forgings that had been accepted by the Ordnance Department and those that had failed to pass the specified physical tests. In general, these tests require a minimum tensile strength of 95,000 lb. (42,091 kg.)! an elastic limit of 65,000 lb. (29,483 kg.), an 18 per cent, elongation, and a 30 per cent. reduction in area. An average chemical composition of the steel studied is 0.38 per cent. carbon and 2.9 per cent. nickel. The steel was of both basic electric and basic open-hearth manufacture. The object of the metallographic work was twofold: to assist in detecting defects in the steel and, if possible, to suggest remedies for the same; and to obtain as much information as possible in regard to the relation of the microstructure of the metal to its physical properties. The grcatcr part of the investigation was devoted to defective metal that failed to pass the ordnance specifications. Many types and kinds of more or less serious defects thus came under observation, but most of these were due to the attempts by the manufacturer to meet the enormous demand for ordnance steel with more or less inadequate equipment, and were soon remedied. Two defects, the so-called "flakes" or "snowflakes" and a certain "fibrous" or "woody" fracture, were encountered so frequently and were so disastrous to the steel that the greater part of the study was devoted to them. As a result much information as to their nature and their effects upon the steel and something in regard to some of the conditions that favor their development has been obtained. The purpose of the present

Jan 1, 1920

By Roger Holmberg, Kenneth Mäki

This paper describe; open pit studies where blasting damage introduced in the remaining rock has been investigated. Results from two open pit mines are described and discussed. Parallel performed laboratory experiments, where simulated blasting damage has been introduced into samples before shear strength testing took place, are also reviewed. These studies are tied together in order to throw some light upon how the blasting damage influences the slope stability. A mathematical model is also described which will make it possible to optimize the blast design for a specified damage zone in the rock mass.

Jan 1, 1983

[Executive E. DEGOLYER, Chairman SYDNEY H. BALL WILLIAM H. Bassett RICHARD PETERS, JR. J. V. W. REYNDERS Finance GEORGE D. BARRON, Chairman H. A. GUESS GEORGE OTIS SMITH]

Jan 1, 1928

THROUGH the courtesy of the Southern Appala-chian Coal Operators' Association, a joint meeting of the Southern Appalachian Efficiency Associa-tion and local members of the A. I. M. E. and A. S. M. E. was held at Knoxville, Tenn., on Nov. 12. In introduc-ing the subject and stating the object of the meeting, H. Foster Bain, speaking for the. Institute members, said "Shoveling coal is the largest job of hand labor re-maining in this country, with the exception of the mis-cellaneous work on the farms, and even there nearly all the big jobs are now performed with the help of machines. The men in the coal mines, by hand labor, dig, each year, more cubic yards than were taken out of the Panama Canal. It has been a natural ambition of engineers, operators and men alike to follow here the characteristic lead of American industry and to substi-tute as far as possible the work of machines for the work of men; to promote the latter to the position of con-trolling and directing mechanical power rather than being themselves the machines that lift the coal from the floor of the room into the mine car. "Handling materials is one of the regular jobs of mechanical engineers, and the American Society of Me-chanical Engineers maintains a Materials Handling Division for discussion of the technical problems con-cerned. Having in mind the excellent results that had flowed from application of mechanical power and de-vices to these problems in factories, port terminals, warehouses, and other above-ground plants, the Me-chanical Engineers began to consider the possibility of introducing similar methods underground. Individual-ly, many were called upon to design, erect and operate machines for such use and at once they found them-selves faced by many novel conditions and difficulties. The Division thereupon planned a general meeting in New York in March, 1926, for consideration of problems and progress in this field. The Mining Engineers. and representative coal operators were invited to attend and

Jan 12, 1927

By R. S. Wagner, R. G. Treuting, W. C. Ellis

Use of the Weisseizbevg goniometer for the study of the morphology of whisker crystals and transfer of the results to a stereograplzic projection are described. While in almost all instances a complete and rapid solution is obtained with a purely gaphical treatment, an absolute analytical treatment applicable to difficult cases is given. Examples are given for determination of growth direction and external features of a crystal, for detection of 'twintzittg, and for establislting the orientation relntionships in a kinked whisker crystal. We give here a method for the use of the Weissen-berg goniometerl" in the study of orientation relationships in "whisker" (micro) crystals3-8 and direct transference of the data to the stereographic projection. The operations are straightforward and require no involved calculations: in almost all cases solely graphical treatment is adequate. In a few complex instances, a more exact analytic method may be required. In the method, not only are equatorial reflections of an oscillation photograph used, but also those on higher layer lines, or those not occurring on a recognized layer line. Such reflections off the zero level are often essentialy to detect the presence of twinning. The method is particularly suitable for examination of whisker crystals since the axial or growth direction is almost always one of high symmetry, permitting a more restricted oscillation range to obtain the necessary reflections and an accordingly shorter exposure time. The method is also applicable when there is no lattice-related external symmetry, and is as well able to identify external crystal surfaces, when such exist, with the aid of an optical beam. Thus growth direction, identification of lateral faces, twinning, and orientation relationships in a kinked crystal can be established. A test for the Eshelby twist6-8 can readily be made. The method can be used for orientation, for structure analysis, and as an aid in the identification of an unknown crystal. Moving-film techniques have previously been employed variously for crystal-orientation studies.1,2,9-13 In particular, use of the Weissenberg method for orientation determination has been reported by Wooster and wooster.14 While their method derives the same data as here described, it differs in depending on the tracing of constant p streaks, a less than dependable phenomenon with small specimens, a few microns or less in cross section. The Laue method can and has been used for orientation studies of microcrystals,15 e.g., 2 p in cross section, but requires the extreme intensity and concentration from a microfocus tube to obtain reasonable exposure time. PRINCIPLES OF THE PRESENT METHOD Consider a crystal of random orientation with respect to the oscillation axis in a Weissenberg goniometer. Its diffraction pattern need not necessarily result in recognizable layer lines. In Fig. 1, a stereo-graphic projection of the reference sphere is given with the equatorial plane XZ normal to the oscillation axis Y, and the X-ray beam directed from X towards 2. The great circle ZZ is then normal to the beam, and the axes are right-handed. Thus the reflected X-ray beam lies at the intersection R of small circle ARB of radius 28 from 2, and of small circle RE of radius a from the rotation axis Y. a is the conventional semiapex angle of a cone of diffracted rays from the atoms aligned in the direction

Jan 1, 1967

By Guy R. Johnson

It is a common observation among those engaged in the ironbusiness, that the lower (i.e., the less graphitic) grades of pigiron show a rough face on the pig. As such irons are always low in silicon, the generally accepted belief is, that this rough face is due to the absence of silicon. Certain investigations, however, made by the writer on Embreville pig-iron, and extending over nearly a year's time, seem to indicate another cause, namely, the giving-off of included gases, particularly sulphurous oxide (SO2,). It is, of course, the tendency of such gases to rise through the iron, escaping into the air; and the more liquid the iron, and the longer it remains liquid, the greater the chance for such escape. The lower grades of iron, being always colder, tend to solidify early, and before the included gases can completely escape.

Jan 1, 1898

By M. Murakami, Y. Murakami, O. Kawano

The formation and growth of Guinier-Preston zones in Al-Zn alloys containing 4.4, 6.8, 9.7, and 12.4 at. pct zn have been studied by the X-ray small-angle scattering method. Particular attention was paid to the effects of small amounts of third elements silver, silicon, and magnesium on the formation and growth of G.P. zones. It was noticed that an appreciable number of G.P. zones were formed during the course of rapid cooling and that the size, volume fraction, and number of these G.P. zones were influenced by the existence of the third elements. During subsequent aging it was also found that the addition of both silver and silicon lowered the temperature for the growth of G.P. zones, whereas the addition of magnesium raised it. These results were explained in terms of the mutual interactions among zinc atoms, vacancies, and the third elements. A number of studies on the formation and growth of Guinier-Preston zones in Al-Zn alloys have been reported.1-4 Panseri and Federighii have found that the initial stages of zone growth take place at temperatures as low as around -100°C. For investigation of the mechanism of the initial stages of zone growth, growth studies must be carried out at low temperatures. In order to investigate the possibility of the formation of G.P. zones by the nucleation mechanism or the spinodal decomposition during quenching which was reported by Rundman and Hilliard,5 the examination of the as-quenched structure must be performed. In this paper the investigation of the early stages of the formation and growth were determined by means of the X-ray small-angle scattering method. With this technique, change of X-ray scattering intensities was measured while quenched specimens were heated slowly from liquid-nitrogen temperature to room temperature. At as-quenched state and after heated to room temperature, investigation of zone size, volume fraction, and zone number per unit volume was carried out. Measurements on these specimens yielded information on the early stages of zone formation and growth. Measurements were made also on specimens quenched to and aged at room temperature. From these measurements the previously reported model6 for the later stages of growth is confirmed; namely, the larger zones grow at the expense of smaller ones. Three elements, silver, silicon, and magnesium, were chosen as the third elements for the following reasons: Silver. In the binary A1-Ag alloy the spherical disordered 77' zones were observed immediately after quenching.7 Therefore, in the Al-Zn-Ag alloys, it is suggested that silver atoms might induce cluster formation during quenching. Also, since the migration energy of the zinc atoms was found to be raised by the addition of silver atoms,' silver atoms may have a great effect of the zinc diffusion, especially during low-temperature agings. Silicon. The effects of the addition of silicon atoms were found to be marked, especially at low-tempera-ture aging. In the binary Zn-Si system, no mutual solid solubilities between silicon and zinc9 and no in-termetallic compounds10 are reported to exist. Shashkov and Buynov11 investigated the behavior of silicon atoms in Al-Zn alloys and showed that silicon was not in the G.P. zones. The interaction between silicon atoms and vacancies is strong enough to increase the quenched-in vacancy concentration.* Magnesium. Magnesium atoms are reported to trap quenched-in vacancies and after much longer aging times these trapped vacancies will become free and act as diffusion carriers.13 Therefore at intermediate aging times, the diffusion of zinc atoms in Al-Zn-Mg alloys will be slower than in the binary Al-Zn alloys, whereas at longer times zinc diffusion will become faster. EXPERIMENTAL PROCEDURE The alloys used in this investigation had compositions of 4.4, 6.8, 9.7, and 12.4 at. pct Zn with or without 0.1 and 0.5 at. pct Ag, Si, or Mg. The alloys were prepared from high-purity aluminum, zinc, silver, silicon, and magnesium, with each metal having a purity better than 99.99 pct. The analyzed composition of the specimens is given in Table I. The measurements of the X-ray small-angle scattering were carried out with foils of 0.20 mm thick. The change of the scattering intensity was always measured at the fixed scattering angle of 20 = 2/3 deg. This angle exists nearly on the position of the intensity maximum. The value of the interparticle interference function14 which has large effect in this range of angles may not change abruptly in the case of the spherical shape of small zones. Therefore, from the above considerations, it is concluded that an increase of the intensity measured at this constant angle corresponds to an increase of the average radius and volume fraction of G.P. zones. The specimens were homogenized at 500°, 450°, and 300°C for 1 hr in an air furnace. For the study of the formation and growth at low temperatures, the foil

Jan 1, 1970

Jan 1, 1934

By W. M. Rust, W. D. Mounce

THE almost universal acceptance of electrical logging by the petroleum industry calls for a critical examination of the physical bases of the common methods. This is particularly needed for the natural potential log. The conventional explanations are based on the phenomena of electrofiltration and electro-osmosis. However, experimental data show that they fail to give a basis that is quantitatively sound. Moreover, they lead to interpretations of details of electrical logs that are erroneous. It was found experimentally that when a plug of shale is placed in a chain of dissimilar electrolytes, a current flow results. Experiments on oil-well cores and fluids similar to those existing in wells show that potentials are set up which are in reasonable agreement with those encountered in electrical logging. Doubt- less other sources of potential are important but this explanation not only accounts for much of the potential but also clarifies some fairly familiar examples of misinterpretations.

Jan 1, 1944

COUNCIL OF SECTION DELEGATES E H Stevens, Chairman James W Halley, Vice-Chairman George J Donaldson, Secretary The Peoples Natural Gas Co 140 Stanwix St Pittsburgh 22, Pa EXECUTIVE COMMITTEE H R Wardwell, J G Evans, H R Bianco, Harry Campbell

Jan 1, 1955

By Wayne Loel

THE application of aerial photographs to all phases of geologic mapping is set forth, indicating the advantages to be gained in different types of country and under varying climatic conditions, Methods of field and office procedure are given from a geological point of view, as well as suggestions regarding the best methods of aerial mapping for different uses and under varying field conditions, including the study of submarine geology. Aerial photographs with accompanying geologic maps are shown to illus-trate the appearance from the air of different geologic features under varying climatic and topographic conditions.

Jan 1, 1938

By Joe O. Ledbetter

INTRODUCTION Health physics as a profession really got a significant start during the Manhattan Project of World War 11. The Health Physics Society has recently published its 25th anniversary issue of the journal (June 1980). There was concern over radiation exposures during and after uranium production, especially about radium and its daughter products [Jackson 19401 and, as evidenced by the frequency of articles in the literature, there still is. The reason for this concern was expressed by Harley as "Workers engaged in the mining and pro- cessing of radium-bearing materials are exposed to dusts of the parent, to radon, and to the radon daughter products. In- haled radioactive particulates may be retained in the lung or redistributed to other organs of the body. Relatively minute de- posits of radioactive substances, particularly alpha emitters, have been clearly shown to be the etiological factor in a variety of injuries to industrial and re- search workers. " [Harley 1953] Emphasis in measurements has been placed on radium in water and radon in air, since these are the principal mobilized phases; however, it should be kept in mind that radium-containing particles do become suspended in air as aerosols and radon absorbs in liquids. Much of the uranium mining and production is being carried out aboveground. The principal difference between underground and surface (pit or leach) mining of uranium is the reversal in the relative importance of roles for the types of radiation dose. For aboveground the major radiation exposure is external gamma ray, whereas for underground it is internal alpha; for aboveground, the whole body penetrating is of greater importance than the lung alpha dose. AS a result of the politics involved and the law- suits for any and all diseases as being occupationally- caused, today , more than ever before, the successful performance of the activities connected with uranium production--before-, during-, and after-the-fact-- must include the provision of first class radiation protection. Such protection can be achieved by good measurements, thorough risk evaluations, and adequate controls. Meeting the ALARA (As Low As Reasonably Achievable) philosophy necessarily entails the determination of what is reasonable exposure. The necessary and sufficient elements of radiation safety under the ALARA dictum require a hard look at the dose versus effects data. There are times when the health physicist needs to make decisions of judgement rather than compliance with a well-defined regulation value. In order to facilitate such decisions, the real world must be separated from opinions that are merely artifacts of statistical variation and from the unprovable "what ifs" that are slanted to question the morality of any non-Luddite. UNITS VOCABULARY FOR DOSIMETRY There have been many radiation quantifying and dosimetric units introduced in the past. Fortunately, most of them did not catch on enough to become required knowledge for reading the health physics literature. The unit definitions necessary for our purposes here are the following: -curie (Ci)--unit of radioactivity equal to 3.7 x 10 10 disintegrations per second Webster&apos;s 19711 or the quantity of radionuclide that undergoes 3.7 x 10 nuclear transformations per second. Environmental levels of radioactivity are usually measured in picocuries (10-l2 Ci) per cubic meter for air and in picocuries per liter (pCi/~) for water and sometimes for air. .roentgen (R)--exposure dose of x or gamma rays that gives 1 esu of charge (either sign) to 1 cc of dry air @ STP. The roentgen is equivalent to an energy absorption of 86.7 ergs/g of air [Gloyna and Ledbetter 19691. .rad--radiation absorbed dose of 100 ergs per gram of absorber. The SI unit for absorbed radiation dose is the Gray; 1 Gy = 100 rads. orem--radiation absorbed dose of 1 rad times the quality factor (QF) for that radiation. The QF is 1 for x rays, gamma rays, beta rays, and posi- trons. For heavy ionizing particulate radiation, QF is a function of the amount of energy trans- ferred per unit length of travel, i.e. , the linear energy transfer (LET); the values of QF:LET in keV/um are as follows: 1:<3.5; 1-2:3.5-7; 2-5:7-23; 5-10:23-53; and 10-20:53-175 [Morgan and Turner 19 671 . For radiobiology, relative biological effectiveness (RBE) is recommended for use instead of the quality factor above that is for radiation protection: the RBE is the ratio of the dose of 200 kVp x rays to the dose of radia- tion in question (both in rads) to cause the same

Jan 1, 1980

Falconbridge Nickel, the one-time subsidiary that grew up to swallow its own parent, Ventures Limited, in 1962, is not about to be left behind by rising nickel consumption. At a cost of several hundred million dollars, this Canadian firm has undertaken a series of new projects that will not only ensure its present share of the market, but also lead it into new areas of the nickel business. Although Falconbridge Nickel Mines Ltd. was not formed until 1928, it actually had its start in 1917- 18 with the discovery of a large, good grade nickel- copper deposit in Falconbridge, near Sudbury, Ontario. However, due to several factors, financing could not be obtained and the orebody lay fallow. It was not until 1928, when the Thayer Lindsley interests bought the property from the original owner, that it was developed.

Jan 10, 1968

By W. O. Philbrook. K M Goldman, M. M. Helzel

RADIOACTIVE calcium has been used to learn whether calcium can be detected in iron saturated with carbon after it has been melted under CaO- A12O3- SiO2 slags similar to those used in the iron blast furnace. It was hoped that the radioactive tracer technique might make possible a general study of steelmaking reactions in which calcium or calcium oxide are involved. No calcium could be found in the metal under conditions which were favorable for the reduction of calcium, and it has been concluded that the calcium content of the iron was less than 6 x 10 - pct. Some of the problems encountered have been instructive with regard to pitfalls and limitations of tracer methods. Calcium oxide occurs in almost all iron- and steelmaking slags, and it is essential to the success of all commercial basic steelmaking processes. Calcium alloys are sometimes used in the deoxidation of steel and for the innoculation of gray iron. The element calcium is therefore almost as ubiquitous in the steel industry as are carbon and oxygen, but calcium has been thought to be completely immiscible with iron in both the liquid and the solid states.&apos; It does not seem entirely unreasonable to Suppose, however, that some low concentration of calcium might exist in liquid iron under a basic slag with other conditions being favorable, just as silicon and other elements can be introduced into iron by reduction of their oxides from slags under appropriate circumstances. The radioactive tracer technique offered a more sensitive method than chemical analysis of testing this supposition. The reasons for interest in this investigation were strong enough to justify a recognized risk of failure. On the theoretical side, information on the distribution of calcium between liquid iron and a slag and the rate at which the equilibrium distribution is approached would contribute strongly to the general theory of slag-metal interface reactions. Furthermore, any evidence on the presence of calcium in liquid iron might provide a vital clue to the mechanism of the desulphurization of iron by slags. All of the reactions which have been proposed to explain desulphurization postulate that the sulphur ultimately becomes fixed in the slag as calcium sulphide, but the mechanism by which sulphur

Jan 1, 1951

By W. H. Adams

Shortly after becoming one of the van-guard of mine-developers in the State of Virginia, during the year 1883, I called the attention of the Institute to certain deposits of pyrites, which have been largely worked since. In all cases these deposits are covered with iron-ore (limonite), extending 40, 50 or 60 feet from surface to water-level. The several classes of brown iron-ores are found almost continuously along a prominent ridge of mineral-bearing slates, which can be traced from the James river northeasterly to the North Anna, the Rappahannock and the Potomac rivers, crossing the counties of Louisa, Spottsylvania and Stafford. Outcrops are plainly discoverable from end to end of this belt, also, in places, to the right and left of it, and at intervals there are evidences of workings, some of them for known purposes and others of unknown age and meaning. These old workings have an interest aside from the minerals they may contain or may have yielded. I have been engaged during the past five years in the collection of facts concerning them, which might determine definitely the site of those iron-furnaces, placed by tradition within reach of " the towne called Germanna," which were the first ever built in this State or on this continent. The events which led to the establishment of this important industry are sufficiently narrated in a paper written by Mr. R. A. Brock, Secretary of the Virginia Historical Society, and printed in the Proceedings of the National Museum, 1885, page 77, from which I quote the following : " To Virginia, the first of the English settlements in America, belongs the honor of inaugurating within her limits, as a colony, that most important industry, iron manufacture. "The London Company contemplated a variety of manufacturing enterprises from the very beginning of its authority; prominent among them was that of iron. In 1610 Sir Thomas Gates testified before the council of the Company at London, that in Virginia &apos; there were divers minerals, especially iron-oare,&apos; lying upon the

Jan 1, 1892

By Charles Austin

IN an earlier series of studies on 18-8 stainless steel at 600°, 700°, and 800°C.1 one pretreatment was used throughout; viz., 15 min. in hydrogen at 950°C., followed by an air quench. Several manufacturers of this alloy since have expressed doubt as to the suitability of the temperature employed, recommending instead the more customary Strauss treatment as promising superior results. In this subsequent investigation on the effects of the temperature of pretreatment several interesting points have arisen, which are described in this paper. Previous work on our equipment had shown a marked difference between alloys of "similar chemical composition" that had been manu-factured by different companies. Accordingly, one mill-bar length was selected from which to prepare all specimens. It could then be assumed that any marked differences in creep characteristics would be due to effects resulting from variations in the pretreatment of the alloy. The material was furnished by the Allegheny-Ludlum Steel Co. in the form of 5/16-in, dia. rod, finished by air cooling from a mill anneal at 1950°F. (1066°C.). It was analyzed only for the elements shown: carbon, 0,07 per cent; chromium, 18.73; nickel, 9.46; manganese, 0.40. Three pretreating temperatures were chosen, the specimens being held for 15 min. in hydrogen at either: (1) 1150°C., to conform to the recom-mended Strauss treatment; (2) 950°C., to compare with the results of previous tests; or (3) 750°C., to initiate precipitation of carbides in the material before testing. As the test cross sections were only 1/8 -in. dia., air cooling followed the annealing treatment. These treatments per-mitted two direct comparisons: (1) between the 1150° and 950°C. treat-ments to indicate the effect of grain size when all carbides were probably in solution at the start of the test; and (2) between the 950° and 750°C. treatments to indicate the effect of carbide "nucleation" for similar grain sizes.

Jan 1, 1940

By A. C. Losekamp, J. B. Conway

Thermal-expansion data for, tungsten, rhenium, tantalum, .molybdenum, niobium, W-25 pct Re, Ta-10 pct W, ant1 Mo-50 pct Re are presented covering the range from room tempature to 2500°C. In these measureMents, made in a resistively heated tungsten tube furnace operating in a helium atmosphere, data for rod and sheet specimens were found to be identical; in addition, arc-cast and sintered tungsten were found to yield essentially identical results. Optical rneasurenlents of thermal expansion .made in any atmosphere other- than vacuum are subject to a refraction error which can be quite substantial. Specimens tested in helium appear shorter than when tested in racuum and hence a special correction factor must be applied to the helium data in order to obtain accurate results. WHILE it is true that linear thermal-expansion data for many of the refractory metals have been measured to very high temperatures, it is also true that except in a few instances the data from various investigators are not in good agreement. This is particularly evident in the case of tantalum and niobium although some tungsten data have been reported which differ by as much as 40 pct from the data of other investigators. Due to the sensitivity of both tantalum and niobium with respect to impurity absorption during exposure to high temperatures, it is probable that this single factor accounts for the majority of the discrepancies in the thermal-expansion data for these metals. However, this same factor can probably not be employed to explain the existing differences in the tungsten data. In all probability, these are due to errors in the measurement technique, to material composition variations, or to changes which take place in the material during the heating process (e.g., additional densifica-tion resulting from heating a sintered specimen above the original sintering temperature). In view of the discrepancies which exist in the linear expansion data reported for many of the refractory metals, the current study was initiated in an attempt to resolve such differences. Also, no high-temperature linear thermal-expansion data were found to be available for several refractory metals. Providing such data was another objective of the current investigation. MATERIALS In this study test specimens were employed in either rod or sheet form and in several instances both arc-cast and sintered material were employed. Material compositions are presented in Table I. Helium gas was fed to the furnace at a rate of about 0.5 SCFH and no special purification procedures were employed. However, the helium contained less than 50

Jan 1, 1967

By William Sellers

tested without knowing anything of their chemical composition. I had these pieces separately placed upon 10-inch bearings under a 7-gross ton lianlrner, a piece of 2½-inch round iron laid upon them as a fuller, and the hammer allotved to fall from 20 inches above the fuller, which, according to Haswell, gave a ldow of 67.75 gross tons. The pieces were then turned orcr, the fuller placed upon the convex surface, and the harnnler allowed to fall from 13 inches above the fuller, giving a blow of 58.46 gross tons. You will see that the rails do aot show ally bigrls of ruptnre, and their color at the points of torture prove them to have been absolutely cold when the test was made. I thirk these rails ought to be reasonably safe in the track. As you see by this piece of the head of one of these rails, I had it plarred, and then some teeth cut in it by a cold clrisel, and one-half of them pounded down with a hammer. The teeth of my rack did not break off. The analyses of these rails substquently made are: I. 11. Carbon,... 0.110 0.880 Silicon,..0.050 0.058 Phosphorus ,..0.086 0.082 Manganese,.. 0.042 0 840 In conclusion, I will say that Dr. Dudley&apos;s paper as a contribu tion to our knowledge of steel rails is valuable and interesting, but I protest against his conclusions king reoeived as manufacturing or comtnercial axioms. From its being presented in the form-of a report to the leading railroad of the country from one of its trusted officers, as well as from the tone of the concluding deductions, it is liable to be so received by railroad men. If any railroad com pany desires rails made under either of Dr. Dudley&apos;s formulas, and are willing to pay a price large enough to cover the loss in making them, dl and good; but so long as the rail makers are compelled to gwrrantee the wear of their rails for a given number of years, justice reqnires that. the composition of the steel from which these rails are made should be left to them. WILLIAM SELLERS, PHILADELPHIA: The very interesting paper upon the wear of steel rails that has just been read preseak the record of a series of investigations that are extreniely valuable, and the deduction that bas been drawn from the results noted seems to be unavoidable; the tests, however, to which it is proposed steel rails shall be subjected hereafter, with a view to determine their quality, sllould

Jan 1, 1881